Pure Completion

The big one: 112% completion, then finish the game. Everything that counts toward Completion plus the extra percentage from the dream and DLC content - the dream bosses, the Colosseum trials, the Grimm questline, the Godmaster pantheons (Embrace the Void) and the White Palace. The mutually-exclusive achievements don't affect the percentage, so 112% is reachable on a single save (you don't need both Nailsmith or both Zote outcomes for the %). The full-completion capstone.